1. Field of the Invention
The present invention relates to a protocol for scheduling communications among nodes in a mobile ad hoc network in such a manner as to avoid or reduce potential interference.
2. Discussion of the Known Art
U.S. Pat. No. 6,996,061 (Feb. 7, 2006) discloses a method of dynamically scheduling time division multiple access (TDMA) mobile communications. An interference level is detected, and a maximum data service rate for each block of requested sessions is calculated based on the detected interference level and certain parameters for each block. The parameters include a requested delay bound, the number of blocks being transmitted, a requested peak data rate and an acceptable minimum data rate, according to the patent.
See also, U.S. Pat. No. 6,798,761 (Sep. 28, 2004) and U.S. Pat. No. 7,304,972 (Dec. 4, 2007), both of which relate to a method and device for establishing communication links among mobile nodes in a communication system wherein each node is provided with a directional or phased array antenna, and a controller that schedules semi-permanent (SP) time slots to establish a link with each neighboring node.
Nodes in a wireless network operating under the known IEEE 802.11 protocol may utilize a RTS/CTS (request to send/clear to send) mode wherein a transmitting node desiring to send a message to a receiving node first sends a RTS frame to the receiving node. The transmitting node then waits for reception of a CTS frame from the receiving node, and only then proceeds to transmit its message.
When attempting to schedule or reserve time slots for future transmissions in a mobile ad hoc network (MANET), the reserving node is constantly challenged by and must compete with so-called hidden terminals that are beyond the immediate carrier sensing range of the node. Notwithstanding the known art, there remains a need for an operating protocol that allows nodes within a network whose topology is likely to change frequently, to schedule their transmissions in a manner that avoids potential interference caused by transmissions of other nodes which may radiate in omnidirectional patterns.